The present invention relates to an improved manual or motor-driven hydraulic drive system for telescopic legs for a table or other apparatus to be vertically movable.
Telescopic legs for adjusting the height of a work surface, such as a table, has become increasingly popular as attempts are made to improve the work environment and provide better working conditions for employees. Thus, adjustable height work surfaces accommodate employees that are either standing or sitting and are of different gender and/or stature. U.S. Pat. Nos. 6,705,239 and 7,246,779, both assigned to the present Assignee, disclose adjustable table legs which utilize hydraulic cylinders to provide vertically adjustable work surfaces. Lift systems which include hydraulic cylinders and electrically driven pumps are sold by Suspa Incorporated, the Assignee of the present invention, under the trademark MOVOTEC®. Such systems allow the retrofitting of table legs with attachable cylinders to provide manual or electrical raising and lowering of tables. The MOVOTEC® brand leg systems, however, cannot be easily converted from a manual crank system to an electrically driven system and, thus, require separate and distinct drive systems.